Video overlay
Anticipated release: 2.2
Video overlay has not been released yet.
Contents
Description
The edgertronic camera supports modifying the pixels in each video frame to overlay text and graphics. The video frames with the overlay applied are then encoded into a video file. To keep from obscuring the captured video, a black border is added to the bottom of each video frame with the overlay being displayed in the black border region.
When enabled, video overlay adds the note text and the frame number to each video frame. The trigger frame number is zero, pre-trigger frames have a negative number and frames captured after the trigger have a positive number.
Customization
Video overlay is supported using two custom GStreamer elements:
- border
- emboverlay
The border element supports XXX parameters and the emboverlay element supports 19 parameters. Because of the general purpose nature of GStreamer, you can do just about anything you want with overlays. Becuase of the general purpose nature of GStream, it is difficult to get correct.
Since video overlay is supported by GStreamer, all customization is done in the GStreamer pipeline file.
Pipeline file
There are two defined names you can include in each section of your customized pipeline files.
| Name | Description |
|---|---|
| border | String containing all parameters and values that is used by the GStreamer border element. The supported parameters are listed below. An equal sign (no spaces) separate the parameter name from its value. parameter name, value pairs are separated by whitespace. |
| overlay_text | String containing GStreamer emboverly element parameters and values relating to text content and rendering. CAMAPI first processes the string to replace fields with camera configuration values.
An equal sign (no spaces) separate a parameter name from its value. Parameter name, value pairs are separated by white space. |
| overlay_logo | String containing GStreamer emboverly element parameters and values relating to graphics logo rendering. |
| overlay_time | String containing GStreamer emboverly element parameters and values relating to time content and rendering. |
| overlay_frame_number | String containing GStreamer emboverly element parameters and values relating to frame numbering rendering. |
| overlay_notes | String containing GStreamer emboverly element parameters and values relating to notes rendering. |
Overlay string syntax
An equal sign (no spaces) separate a parameter name from its value. Parameter name, value pairs are separated by whitespace. You can escape a character (such as the space character) using a backslash. Use two percent (%) signs instead of one.
overlay_settings
The defined parameters for controlling which camera settings are included and how they are rendered includes:
| Name | Type | Data Range |
Example Value | Description |
|---|---|---|---|---|
| settings-text | string | %%f\ fps | String to be rendered with substitutions for various camera settings. | |
| settings-offseth | integer | -frame width .. frame width | 100 | Horizontal location to start overlay placement. |
| settings-offsetv | integer | -frame width .. frame width | -100 | Vertical location to start overlay placement. |
| settings-font-height | integer | -frame width .. frame width | 60 | Font size (REVISIT: explain units). |
| setting-scolor | integer | -frame width .. frame width | 0xFF0000 | 24 bit color value in the format 0xRRGGBB. |
| enable-settings | boolean | true .. false | true |
The defined 'settings-text camera settings variables include:
| Variable | Camera Setting |
|---|---|
| %%d | Trigger date (DD-MMM-YY) |
| %%t | Trigger time (HH-MM-SS) |
| %%T | Trigger time (seconds since Jan 1, 1970) |
| %%i | Sensitivity (ISO) |
| %%s | Shutter |
| %%f | Frame rate |
| %%S | Sub-sampling |
| %%o | Overclock |
| %%e | Extended dynamic range |
| %%g | Genlock |
| %%b | Multishot buffer |
| %%n | Serial number |
| %%N | Name of file |
| %%F | Scaled font size |
| %%x | Camera calculated x (horizontal) position |
| %%y | Camera calculated y (vertical) position |
Example settings string:
%%f\ fps\ \ %%b\ buffer
Example configuration strings
The follow examples can be included in your custom GStream pipeline files.
Control the placement and size of the notes text. A negative vertical offset means from the bottom of the video frame.
emboverlay=text-offseth=100 text-offsetv=-100 text-font-height=60 text-color=0xFF0000 enable-text=true
border parameters
emboverlay parameters
logo : Overlayed image path, must be a png file
flags: readable, writable
String. Default: null Current: null
text : Overlayed text to display
flags: readable, writable
String. Default: null Current: null
logo-offseth : Overlayed image horizontal offset
flags: readable, writable
Integer. Range: -2147483648 - 2147483647 Default: 0 Current: 0
logo-offsetv : Overlayed image vertical offset
flags: readable, writable
Integer. Range: -2147483648 - 2147483647 Default: 0 Current: 0
logo-transp : Overlayed image transparency. Enable = 1 Disable = 0
flags: readable, writable
Integer. Range: 0 - 1 Default: 0 Current: 0
enable-logo : Enable or disable logo rendering
flags: writable
Boolean. Default: false Write only
text-offseth : Overlayed text horizontal offset
flags: readable, writable
Integer. Range: -2147483648 - 2147483647 Default: 0 Current: 0
text-offsetv : Overlayed text vertical offset
flags: readable, writable
Integer. Range: -2147483648 - 2147483647 Default: 0 Current: 0
text-font-height : Overlayed text font height
flags: readable, writable
Integer. Range: -2147483648 - 2147483647 Default: 0 Current: 0
text-color : Overlayed text color. RGB format 0xRRGGBB
flags: readable, writable
Integer. Range: -2147483648 - 2147483647 Default: 0 Current: 0
text-border : Overlayed text border color. RGB format 0xRRGGBB
flags: readable, writable
Integer. Range: -2147483648 - 2147483647 Default: 0 Current: 0
enable-text : Enable or disable text rendering
flags: writable
Boolean. Default: false Write only
time-offseth : Overlayed time horizontal offset
flags: readable, writable
Integer. Range: -2147483648 - 2147483647 Default: 0 Current: 0
time-offsetv : Overlayed time vertical offset
flags: readable, writable
Integer. Range: -2147483648 - 2147483647 Default: 0 Current: 0
time-font-height : Overlayed time font size
flags: readable, writable
Integer. Range: -2147483648 - 2147483647 Default: 0 Current: 0
time-color : Overlayed time font color. RGB format color=0xRRGGBB
flags: readable, writable
Integer. Range: -2147483648 - 2147483647 Default: 0 Current: 0
time-param : Overlayed time parameters %b %Y; %H:%M:%S will render: month year; hour:minutes:seconds
flags: readable, writable
String. Default: null Current: null
time-border : Overlayed time border color. RGB format color=0xRRGGBB
flags: readable, writable
Integer. Range: -2147483648 - 2147483647 Default: 0 Current: 0
enable-time : Enable or disable time rendering
flags: writable
Boolean. Default: false Write only
Time overlay
By default emboverly time capability is disabled, because the time used is not the time when the video was captured.
The time-param field is just passed to strftime(), which itself supports 44 parameters. The time used for the overlay is the time when the file is saved, not when the video was captured. Use the metadata file to determine the time the video was captured.
